Field of the Invention
The present invention concerns an actuated device for grasping in a controlled manner an elongated body, as well as a robotized device comprising at least one such grasping device and using it to handle said elongated body.
A preferred application context of the invention is the grasping and manipulation of surgical needles which represent a very common concern in many medical specialties involving image guided needle insertions, in particular in the context of interventional radiology.
In this medical specialty, minimally invasive procedures are performed to diagnose or treat pathologies under image guidance.
The medical interventions mainly targeted here encompass the wide class of procedures that necessitate needle insertion such as biopsies, radiofrequency ablations or cancer local delivery treatments.
To ensure a proper safety level in the procedures, visual feedback is usually mandatory to monitor the instrument insertion.
Among the various imaging modalities available, computed tomography (CT) and fluoroscopy provide a fast and accurate visual feedback to the radiologist and are now very widely used in medical routine.
However, repeated CT and fluoroscopy endanger physicians with potentially harmful ionizing radiations.
That is one of the main motivation for developing teleoperated robotic assistant devices to remotely insert needles or similar elongated bodies under CT guidance.
Description of the Related Art
A possible layout of teleoperated percutaneous procedures was presented in Piccin, O., Barbé L., Bayle, B., de Mathelin, M. and Gangi, A., 2009: “Force feedback teleoperated needle insertion device for percutaneous procedures”, International Journal of Robotics Research, 28(9), September, pp. 1154-1168, Special issue on Medical Robotics.
It is composed of a master station protected from the radiation source and operated by the physician using a haptic interface.
At the remote site, the slave station comprises the CT scanner, the patient and the robotic assistant dedicated to the percutaneous procedure.
This layout enables the radioprotection of the medical staff but also provides the practitioner with a haptic feedback on the insertion task which is highly desirable for safety reasons.
As a consequence, the development of needle grasping devices is an important subject for the previously targeted applications.
The available space between a CT-scan ring and a patient is a prominent limiting factor. The corresponding volume corresponds typically to a 200 mm radius hemisphere which is just slightly higher than the length of most biopsy needles. Consequently, the grasping device size should be as small as possible.
In addition, it would be beneficial to comply with existing surgical needles, in terms of diameter, length and general constitution, and thus avoid the use of device specific needles.
Another important feature for the needle grasping device is the capacity to allow a wide aperture around the needle when opened as well as to get the needle automatically and necessarily centered during re-grasping of the needle (keeping a secure loose hold on the needle).
This demand originates from the fact that the needle insertion is not a one step task.
Indeed to avoid internal tissue laceration and improve gesture accuracy, the insertion motion itself is generally done during a short patient's apnea. After that, the non-inserted part of the needle requires to be released to comply with the motion exerted by the internal perforated organs.
At this stage, the needle should move freely off a central position about the entry point on the patient's skin.
To perform the following insertion step the grasping device should be capable to re-center and re-grasp the needle.
One optional but very desirable feature of the grasping device corresponds to the possibility of rotating the needle about its axis to facilitate the needle steering.
Concerning force transmission, the grasping device should be able to sustain a maximum insertion action of about 15N, allow haptic feedback, more precisely, and be compatible with real-time insertion force measurement.
To avoid needle deterioration, the grasping device should ideally incorporate a grip limiting scheme.
Concerning the constitutive material requirements, the grasping device should not generate artefacts in CT scanner images.
And the concluding items in this requirement list are the safety and sterilization properties pertaining to the medical context.
Systems dedicated to needle manipulation are very scarce in prior art and literature and use mostly opposing rollers to perform simultaneously the needle grasping as well as its insertion motion (see for examples: Stoianovici, D., Cleary, K., Patriciu, A., Mazilu, D., Stanimir, A., Craciunoiu, N., Watson, V. and Kavoussi, L., 2003: “Acubot: a robot for radiological interventions”, Robotics and Automation, IEEE Transactions on, 19(5), October, pp 927-930/Walsch, C. J., Hanumara, N. C., Slocum, A. H., Shepard, J.-A. and Gupta, R., 2008: “A patient-mounted, telerobotic tool for CT-guided percutaneous interventions”, Journal of Medical Devices, 2(1), p. 011007.
This working principle makes it very difficult to measure axial insertion forces.
To add this important functionality, it seems necessary to uncouple the needle displacement from its grasping.
This issue has been addressed in the system described in Badaan, S., Petrisor, D., Kim, C., Mozer. P., Mazilu, D., Gruionu, L., Patriciu, A., Cleary, K. and Stoianovici, D., 2011: “Does needle rotation improve lesion targeting?”, The International Journal of Medical Robotics and Computer Assisted Surgery”, 7(2), pp. 138-147.
But the proposed embodiment does not provide a controlled feature for recentering and gripping back the needle during insertion.
This functionality was included in the needle grasping device disclosed in the previously mentioned publication of Piccin, O. et al.
An other existing solution which allows to overcome the drawbacks of previous devices and achieves to fulfil at least the main requirements exposed herein before, and can be considered as an improvement of the solution of the previously mentioned publication of the International Journal of Robotics Research has been disclosed in EP-A-1 871 26 (US 2008/167663) and in: Piccin, O., Renaud, P., Barbé, L., Bayle, H., Maurin, B. and de Mathelin, M., 2005: “A robotized needle insertion device for percutaneous procedures”, In. Proceedings of the 2005 ASME Design Engineering Technical Conferences, pp. 433-440, as several construction embodiments.
In this latter solution, the grasping device consists in at least one annular chuck or mandrel through which the elongated body extends.
Each chuck comprises a main body with a fixed part and a moving part and three jaws which move radially when the moving part is actuated. More precisely, the moving part is in the form of a gear and the jaws are driven by said gear by means of a groove/rib or a rod/slot mechanism, and guided in translation radially.
The chuck can be tightened and opened by rotating the gear member in opposite directions, which causes the jaws to move simultaneously between and extended position near the center of the through passage and a retracted position away from said center, wherein said jaws are located within the thickness of the cylindrical wall of the tubular main body.
Nevertheless, this last existing solution also shows some drawbacks:
1. The grasping force available at the jaws is quite limited, as well as the axial forces applicable to the elongated body;
2. The design and manufacturing of all components, as well as the assembling, need to be done with uttermost precision to achieve simultaneity of movement and centered grasping;
3. The construction design requests that all parts need to be made of rigid material, in particular the components involved in the transmission and transformation of the movement, which latter in addition need to be as small as possible (considering the opposed constraints of limited available free volume and maximum diameter of the through passage in open state), resulting in critical issues as far as manufacturing precision and mechanical slack are concerned (in particular in relation to previous points 1 and 2);
4. A possible jamming of the mechanism cannot be completely avoided (precise translational guiding).